diff --git a/abstract_wayland_output.h b/abstract_wayland_output.h
--- a/abstract_wayland_output.h
+++ b/abstract_wayland_output.h
@@ -64,7 +64,7 @@
         return !m_waylandOutput.isNull();
     }
 
-    virtual QSize pixelSize() const = 0;
+    QSize pixelSize() const;
     qreal scale() const override;
 
     /**
diff --git a/abstract_wayland_output.cpp b/abstract_wayland_output.cpp
--- a/abstract_wayland_output.cpp
+++ b/abstract_wayland_output.cpp
@@ -54,12 +54,7 @@
 
 QRect AbstractWaylandOutput::geometry() const
 {
-    // TODO: This is inefficient on current KWayland since
-    //       we loop over modes.
-//    const QSize size = m_waylandOutputDevice->pixelSize();
-    const QSize size = pixelSize();
-
-    return QRect(globalPos(), size / scale());
+    return QRect(globalPos(), pixelSize() / scale());
 }
 
 QSize AbstractWaylandOutput::physicalSize() const
@@ -93,6 +88,11 @@
     }
 }
 
+QSize AbstractWaylandOutput::pixelSize() const
+{
+    return orientateSize(m_waylandOutputDevice->pixelSize());
+}
+
 qreal AbstractWaylandOutput::scale() const
 {
     return m_waylandOutputDevice->scaleF();
diff --git a/plugins/platforms/drm/drm_output.h b/plugins/platforms/drm/drm_output.h
--- a/plugins/platforms/drm/drm_output.h
+++ b/plugins/platforms/drm/drm_output.h
@@ -60,8 +60,6 @@
     bool present(DrmBuffer *buffer);
     void pageFlipped();
 
-    QSize pixelSize() const override;
-
     // These values are defined by the kernel
     enum class DpmsMode {
         On = DRM_MODE_DPMS_ON,
diff --git a/plugins/platforms/drm/drm_output.cpp b/plugins/platforms/drm/drm_output.cpp
--- a/plugins/platforms/drm/drm_output.cpp
+++ b/plugins/platforms/drm/drm_output.cpp
@@ -675,11 +675,6 @@
     setWaylandMode();
 }
 
-QSize DrmOutput::pixelSize() const
-{
-    return orientateSize(QSize(m_mode.hdisplay, m_mode.vdisplay));
-}
-
 void DrmOutput::setWaylandMode()
 {
     AbstractWaylandOutput::setWaylandMode(QSize(m_mode.hdisplay, m_mode.vdisplay),
diff --git a/plugins/platforms/fbdev/fb_backend.h b/plugins/platforms/fbdev/fb_backend.h
--- a/plugins/platforms/fbdev/fb_backend.h
+++ b/plugins/platforms/fbdev/fb_backend.h
@@ -38,16 +38,10 @@
     ~FramebufferOutput() override = default;
 
     void init(const QSize &size);
-    QSize pixelSize() const override {
-        return m_pixelSize;
-    }
 
     void setRawPhysicalSize(const QSize &set) {
         AbstractWaylandOutput::setRawPhysicalSize(set);
     }
-
-private:
-    QSize m_pixelSize;
 };
 
 class KWIN_EXPORT FramebufferBackend : public Platform
diff --git a/plugins/platforms/fbdev/fb_backend.cpp b/plugins/platforms/fbdev/fb_backend.cpp
--- a/plugins/platforms/fbdev/fb_backend.cpp
+++ b/plugins/platforms/fbdev/fb_backend.cpp
@@ -39,7 +39,6 @@
 
 void FramebufferOutput::init(const QSize &size)
 {
-    m_pixelSize = size;
     KWayland::Server::OutputDeviceInterface::Mode mode;
     mode.id = 0;
     mode.size = size;
diff --git a/plugins/platforms/hwcomposer/hwcomposer_backend.cpp b/plugins/platforms/hwcomposer/hwcomposer_backend.cpp
--- a/plugins/platforms/hwcomposer/hwcomposer_backend.cpp
+++ b/plugins/platforms/hwcomposer/hwcomposer_backend.cpp
@@ -506,7 +506,6 @@
     if (pixel.isEmpty()) {
         return;
     }
-    m_pixelSize = pixel;
 
     if (attr_values[2] != 0 && attr_values[3] != 0) {
          static const qreal factor = 25.4;
@@ -531,22 +530,17 @@
 
     const auto outputGroup = kwinApp()->config()->group("HWComposerOutputs").group("0");
     setScale(outputGroup.readEntry("Scale", 1));
-    setWaylandMode(m_pixelSize, mode.refreshRate);
+    setWaylandMode(pixel, mode.refreshRate);
 }
 
 HwcomposerOutput::~HwcomposerOutput()
 {
     hwc_close_1(m_device);
 }
 
-QSize HwcomposerOutput::pixelSize() const
-{
-    return m_pixelSize;
-}
-
 bool HwcomposerOutput::isValid() const
 {
-    return m_pixelSize.isValid();
+    return isEnabled();
 }
 
 void HwcomposerOutput::updateDpms(KWayland::Server::OutputInterface::DpmsMode mode)
diff --git a/plugins/platforms/virtual/virtual_output.h b/plugins/platforms/virtual/virtual_output.h
--- a/plugins/platforms/virtual/virtual_output.h
+++ b/plugins/platforms/virtual/virtual_output.h
@@ -39,8 +39,6 @@
 
     void init(const QPoint &logicalPosition, const QSize &pixelSize);
 
-    QSize pixelSize() const override;
-
     void setGeometry(const QRect &geo);
 
     int gammaRampSize() const override {
@@ -55,8 +53,6 @@
     Q_DISABLE_COPY(VirtualOutput);
     friend class VirtualBackend;
 
-    QSize m_pixelSize;
-
     int m_gammaSize = 200;
     bool m_gammaResult = true;
 };
diff --git a/plugins/platforms/virtual/virtual_output.cpp b/plugins/platforms/virtual/virtual_output.cpp
--- a/plugins/platforms/virtual/virtual_output.cpp
+++ b/plugins/platforms/virtual/virtual_output.cpp
@@ -46,15 +46,10 @@
     setScale(1.);
 }
 
-QSize VirtualOutput::pixelSize() const
-{
-    return m_pixelSize;
-}
-
 void VirtualOutput::setGeometry(const QRect &geo)
 {
-    m_pixelSize = geo.size();
-    setRawPhysicalSize(m_pixelSize);
+    // TODO: set mode to have updated pixelSize
+    setRawPhysicalSize(geo.size());
     setGlobalPos(geo.topLeft());
 }
 
diff --git a/plugins/platforms/wayland/wayland_output.h b/plugins/platforms/wayland/wayland_output.h
--- a/plugins/platforms/wayland/wayland_output.h
+++ b/plugins/platforms/wayland/wayland_output.h
@@ -62,8 +62,6 @@
 
     virtual bool pointerIsLocked() { return false; }
 
-    QSize pixelSize() const override;
-
     /**
      * @brief defines the geometry of the output
      * @param logicalPosition top left position of the output in compositor space
@@ -95,7 +93,6 @@
     KWayland::Client::Surface *m_surface;
     WaylandBackend *m_backend;
 
-    QSize m_pixelSize;
     bool m_rendered = false;
 };
 
diff --git a/plugins/platforms/wayland/wayland_output.cpp b/plugins/platforms/wayland/wayland_output.cpp
--- a/plugins/platforms/wayland/wayland_output.cpp
+++ b/plugins/platforms/wayland/wayland_output.cpp
@@ -69,14 +69,9 @@
     setScale(backend()->initialOutputScale());
 }
 
-QSize WaylandOutput::pixelSize() const
-{
-    return m_pixelSize;
-}
-
 void WaylandOutput::setGeometry(const QPoint &logicalPosition, const QSize &pixelSize)
 {
-    m_pixelSize = pixelSize;
+    // TODO: set mode to have updated pixelSize
     setRawPhysicalSize(pixelSize);
     setGlobalPos(logicalPosition);
 }
diff --git a/plugins/platforms/x11/windowed/x11windowed_output.h b/plugins/platforms/x11/windowed/x11windowed_output.h
--- a/plugins/platforms/x11/windowed/x11windowed_output.h
+++ b/plugins/platforms/x11/windowed/x11windowed_output.h
@@ -59,8 +59,6 @@
 
     void setWindowTitle(const QString &title);
 
-    QSize pixelSize() const override;
-
     /**
      * @brief defines the geometry of the output
      * @param logicalPosition top left position of the output in compositor space
@@ -75,7 +73,6 @@
     NETWinInfo *m_winInfo = nullptr;
 
     QPoint m_hostPosition;
-    QSize m_pixelSize;
 
     X11WindowedBackend *m_backend;
 };
diff --git a/plugins/platforms/x11/windowed/x11windowed_output.cpp b/plugins/platforms/x11/windowed/x11windowed_output.cpp
--- a/plugins/platforms/x11/windowed/x11windowed_output.cpp
+++ b/plugins/platforms/x11/windowed/x11windowed_output.cpp
@@ -134,14 +134,9 @@
 #endif
 }
 
-QSize X11WindowedOutput::pixelSize() const
-{
-    return m_pixelSize;
-}
-
 void X11WindowedOutput::setGeometry(const QPoint &logicalPosition, const QSize &pixelSize)
 {
-    m_pixelSize = pixelSize;
+    // TODO: set mode to have updated pixelSize
 
     // Physicial size must be adjusted, such that QPA calculates correct sizes of
     // internal elements.